58 



VIEWS OF THE MICROSCOPIC WORLD. 



Fig. 88. 



imalcule, which occurs abundantly in the chalks of France, and is also found in 

 those of England. A profile of this shell, magnified twelve times, arid bearing 

 some resemblance to a fan, is shown in figure 86. When a side view is taken, 

 and the fossil is highly magnified, the beauty of the structure becomes more ap- 

 parent, and the fluted projections, d d, are revealed as elegant spiral shells, 

 divided into several apartments, and presenting an appearance similar to that 

 which is exhibited in figure 87. 



The Textularia or entwined animalcule has the figure of a cluster 

 of globes, rising in the form of a pyramid, and when a section is made 

 in the direction of its length, it displays the different cells into which 

 the cavity of the shell is divided. In figure 88 is shown a specimen 

 from the marl of the Mount of Olives, and an outline of the Ameri- 

 can entwined animalcule is exhibited in figure 89. This species dif- 

 fers in some respects from other Textularia, being wholly local and pe- 

 culiar to the chalk marls of the Upper Missouri ; of which vast 

 deposit it forms the principal part. The living Xanthidia, or 

 Cross-bar animalcules, have already been described ; and in 

 figures 90, 91, 92 and 93 are presented several specimens as 

 they appear in flint. In this stone they often occur in great 

 abundance, no less than twenty being once discovered by Mr. 

 Hamlin Lee, in a chip of flint, the surface of which was 

 scarcely the twelfth of an inch in diameter. These Infusoria 

 are easily detected in flints which are translucent ;. the only 

 preparation required being simply to select the thinnest and 

 clearest flakes, struck off by the blow of a hammer, and before 

 Viewing them with a microscope, to immerse them in oil of tur- 

 pentine, in order to render them more transparent. The specimens of Xanthi- 

 dia represented in figures 90, 91, 92 and 93, were taken from a remarkable 



Fig. 90. 



Fig. 91. 



Fig. 92. 



Fig. 93. 



group, described by Dr. Mantell, and found by his son in a flake of flint. This 

 flake is delineated of its natural size in figure 90 ; in figure 91 it is considerably 

 magnified, and the several fossils are distinctly seen. Figures 92 and 93 are 

 two of the specimens very highly magnified, and are a variety of the Branched 

 Xanthidium, which is found only in a fossil state. That they belong to the race 

 of the Xanthidia is evident from the resemblance they bear to the drawings of the 

 living specimens, figures 40 and 41. Five specimens were found in this fragment of 



